Generally, interactive services such as multicast, broadcast and video telephony, and streaming services such as Video on Demand (VOD) service are referred to as multimedia services. The multimedia services may be classified into real-time multimedia services and non-real-time multimedia services. The real-time multimedia services may be classified into unicast services, multicast services and broadcast services depending on the number of users thereof. In addition, the real-time multimedia services may be classified into interactive services and streaming services depending on the type of service.
In the related-art multimedia network, Moving Picture Experts Group (MPEG)-2 Transport Stream (TS) has been used for transmission of multimedia content. MPEG-2 TS has been used as a transmission technology for transmitting a multiplexed bit stream of a plurality of multimedia programs (e.g., a plurality of coded video bit streams) in a transmission environment that provides a fixed bandwidth having errors. For example, MPEG-2 TS has been suitably used in multimedia devices such as digital TeleVisions (TVs) in the age of multimedia.
FIG. 1 illustrates a hierarchical structure for supporting MPEG-2 TS according to the related art.
Referring to FIG. 1, layers for supporting MPEG-2 TS may include a media coding layer 110, a synchronization (sync) layer 120, a delivery layer 130, a network layer 140, a data link layer 150, and a physical layer 160.
The media coding layer 110 and the sync layer 120 may be configured in a format, in which media data can be written, or that can be easily used as a basic unit of transmission. The delivery layer 130, the network layer 140, the data link layer 150 and the physical layer 160 may configure a data block (e.g., Access Unit (AU)) in the format configured by the sync layer 120, as a multimedia transport packet to be written in a separate recording medium or to be transmitted. The configured multimedia transport packet may be transmitted to a subscriber terminal over a predetermined network.
To this end, the sync layer 120 may include a fragment block 122 and an access unit 124. The delivery layer 130 may include MPEG-2 TS/MP4 Real Time Transport Protocol (RTP) Payload format/File deLivery over Unidirectional Transport (FLUTE) 132, RTP/Hyper Text Transfer Protocol (HTTP) 134, and User Datagram Protocol (UDP)/Transmission Control Protocol (TCP) 136.
However, MPEG-2 TS may have several limitations in supporting multimedia services. Specifically, the limitations of MPEG-2 TS may include one-way communication, inefficiency of transmission due to fixed packet size, and unnecessary handover which may occur when data is transmitted using a transport protocol specific to audio/video and an Internet Protocol (IP).
Therefore, an MPEG Media Transport (MMT) standard has been newly proposed by MPEG as one of the multimedia transport technologies for supporting multimedia services based on the MPEG technology. In particular, the MMT standard has been proposed by MPEG to overcome the limitations of MPEG-2 TS.
For example, the MMT standard may be applied to efficiently transmit hybrid content over a heterogeneous network. The term ‘hybrid content’ as used herein may refer to a set of content having multimedia elements by audio, video, applications and the like. The term ‘heterogeneous network’ as used herein may refer to a network in which a multimedia network, a communication network and the like are mixed.
Besides, the MMT standard aims to define the IP-friendly transmission technology which is now the basic technology in the transmission network for multimedia services.
Therefore, continuous research and standardization have been conducted on the MMT standard for providing efficient MPEG transport technology in the typical multimedia service environment that varies based on IP.
In particular, in the MMT standard, there is a need for a way to provide efficient MPEG transport technology in the hybrid network environment in which a single terminal is connected to a plurality of networks and provides multimedia services, and in the recent multimedia service environment designed to provide hybrid content that is composed of not only the audio and video data but also the application, widget, image and the like, and that can be consumed in a user's terminal.
The above information is presented as background information only to assist with an understanding of the present disclosure. No determination has been made, and no assertion is made, as to whether any of the above might be applicable as prior art with regard to the present disclosure.